Splash mixer for dental castings



. D. .PELLERGRINI SPLASH MIXER FOR DENTAL CASTINGS Filed Sept. 16, 1949Sept. 29, 1953 Patented Sept. 29, 1953 I r I I 2,653,361

UNITED STATES PATENT OFFICE 7 2,653,361 SPLASH MIXER FOR DENTAL CASTINGSV Domenick Pellegrini, Yonkers, N. Y.

Application September 16, 1949, Serial No. 116,109

1 Claim. 1

This invention relates to new and useful improvements in devices formaking dental castings.

An object of the invention is to provide a simple means whereby castingscan be much more quickly produced than before.

A further object is to provide a simple and veiiicient device in whichthe wax pattern for the dental casting may be more easily, effectivelyand quickly coated before being put in the casting mold.

Further and more specific objects, features, and advantages will moreclearly appear from a consideration of the detailed specificationhereinafter set forth especially when taken in connection with theaccompanying drawings which illustrate a present preferred form whichthe invention may assume and which form part of the specification.

In the usual now known methods of making wax patterns, the cavity die isgenerously coated with an oil to prevent the molten wax from sticking tothe inner surfaces of the die, so that the pattern may be removed fromthe die without distortion. This oil must be meticulously removed fromthe surface of the wax pattern before it is coated with the investmentmaterial. This is usually done by carefully washing the surface of thewax pattern with a camels hair brush which has been dipped in somegrease dissolving solution. This operation often causes breaking andchipping of the feather-like edge margins of the pattern, which are themost important part of any dental restoration.

Secondly, the investment of powder and water is mixed and in order toobtain the proper consistency of the mix, the water and the powder aregenerally weighed. This investment compound is mixed by spatulation,generally in a rubber bowl. Regardless of how well the mix isspatulated, it seldom is possible to fully eliminate the small lumps ofpowder which always exist in these investments. After this, thisinvestment is applied to the wax pattern with the same camel's hairbrush with all the attendant difiiculties therewith involved. Inapplying the investment to the pattern, it must be painted on and beblown off several times with the mouth until the pattern is evenlycoated.

After sufficient coating is thus evenly applied, a metal casting ring orshell is placed around the sprue form with the inlay pattern attached toit and the ring is filled with investment. After many years experiencewith this method, it has been found that at least 5% failures result.

In this business, this percentage is not good enough, because a missmeans delay and time does not permit of possessing another pattern.

In contemplating the difficulties and disadvantages of the usual methodabove described, I have developed my new procedure and have found afterexhaustive experiments and tests, that I have cast over 2,000 inlayswithout a single failure and in much less time and with greatly lesslabor and care called for.

In brief and general terms, there is first determined the amount ofliquid and investment powder to be used by measurement and then theseare poured into a container such as a glass jar with a screw-threadedcap, from which depends a wire stem on the lower end of which issupported the wax pattern formed in the usual manner. Beneath the capand surrounding the pattern on the side and the bottom, is a perforatedbasket interposed between the pattern and the creamy liquid formed bythe mixture of the water and the investment powder. I then shake thecontainer for a matter of about a half minute, and find that theinvestment cream has been thoroughly mixed and in a manner homogenized,and that the pattern has been coated properly and evenly with a veryfinely divided material. After this brief shaking has effectedsufficient coating of the pattern, the cap of the container is taken ofiand inverted with a casting shell around the pattern and with the ringfilled with the remainder of the investment which is then allowed toset. This whole operation takes about a minute whereas the formermethod, required from 3 to 5 minutes and was not at all certain.

The present preferred form which the invention may assume is illustratedin the drawings, of which:

Fig. 1 is a vertical cross sectional view of my improved splash mixer;and,

Fig. 2 shows the pattern after being treated in the splash mixer and nowdisposed in the casting mold.

Referring now to the particular form of the invention shown in thedrawings, it is seen that there is provided a container preferably inthe form of a cup of glass or similar material 10, having a top edgethreaded as at H to receive a similarly threaded flanged cap I2, whichmay be made of metal but referably is made of composition such asrubber.

Disposed within the top of the container I0 is a metal basket l3provided with a plurality of holes l4 therein in the sides as well as inthe bottom. This basket has at its top edge, a horizontal flange Iresting on the top edge of the container 10. The inner surface of thecap I2 is lined with a metal lining l6 suitably connected thereto in anydesired manner and having a central depressed portion I! to form acavity to be filled with material such as Wax 18. The depressedcup-shaped portion at its center, is broken away as at I 9 to permit astem or wire 20 to be inserted into the wax. On the lower end of thisstem 20 is mounted the pattern 2i. This stem 20 extends down far enoughso as to suspend the pattern 2| in the middle of the basket I3 justabove the bottom thereof. This depressed portion I9 represents the sprueform so as to result in the sprue in the mold later to be made anddescribed hereinafter.

In the operation of this splash mixer, I place in the container I0 asuitable quantity of investment powder and water with an oil solvent tomake a creamy solution and with this in the container I0 and the waxpattern in place, as shown in Figure 1, I shake the device for a matterof about thirty seconds. During this shaking, the liquid, as itviolently contacts the basket, is thoroughly agitated to break up thepowder into the finest possible consistency so that in a sense, it isthoroughly homogenized and simultaneously theoil, which is generallyfound on the wax patterns, is removed and a coating is formed on thepattern in such a finely divided shape as to be unusually eirective andwhich eliminates the usual washing and painting with a brush which isthe usual procedure.

After this operation, the cap is removed with the sprue form and thecoated wax pattern and laced on a surface upside down, as shown inFigure 2. In this position, a thin cylindrical shell-like mold element22 is placed around the sprue form to inclose the wax pattern 2i and theremainder of the creamy liquid in the container i0, is then poured intothe mold element 22 to form the casting 23. After this casting is set,it is treated and handled in the usual manner.

While the invention has been described in detail and with respect to thepreferred form shown in the drawings, it is not to be limited to suchdetails and forms since many changes and modifications may be made inthe invention without departing from the spirit and scope of theinvention in its broadest aspects. Hence, it is intended to cover anyand all forms and modifications of the invention which may come withinthe language or scope of the appended claim.

What I claim as my invention, is:

A splash mixer for producing investment molds for dental castings whichcomprises a container having a threaded upper end, a cap flanged andthreaded to be engaged with the upper end of the container, a metallining on the cap with a dependent central apertured portionconstituting a sprue form, said sprue form being adapted to be filledwith a composition, a wire stem extending into said sprue form, a waxpattern on the lower end of the wire, a basket having an upper flangeresting on the upper edge of the container and being perforated alongits bottom and sides and disposed around the sides and below the bottomof the pattern, a gasket of ring-shape form resting on said flange to begripped between the flange and the cap, said container being adapted toreceive an investment slurry of water and powder, said pattern beingadapted to be coated by said investment material when said container isagitated.

DOMENICK PELLEGRINI.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,325,004 Davidson Dec. 16, 1919 2,490,193 Barr Dec. 6, 19492,507,867 Pomes May 16, 1950

